Systems for computer-aided detection (“CAD”) assist radiologists in the detection and classification of abnormal lesions in medical images. The purpose of such devices, as described in U.S. Pat. No. 5,815,591 to Roehrig, et. al., entitled “Method and Apparatus for Fast Detection of Spiculated Lesions in Digital Mammograms,” the disclosure of which is hereby incorporated by reference in the present application, is to direct the attention of a radiologist to suspicious areas of the medical image that may reflect a threatening condition. While not a replacement for the experienced radiologist, CAD systems are designed to increase efficiency and reduce error, as a typical radiologist may be required to examine hundreds of medical images per day, which can lead to the possibility of a missed diagnosis due to human error.
Various systems and methods are currently known for computerized detection of abnormalities in radiographic images, such as those disclosed by Giger et al. in RadioGraphics, May 1993, pp. 647–656; Giger et al. in Proceedings of SPIE, Vol. 1445 (1991), pp. 101–103; U.S. Pat. No. 4,907,156 to Doi et al.; U.S. Pat. No. 5,133,020 to Giger et al.; U.S. Pat. No. 5,343,390 to Doi et al.; U.S. Pat. No. 5,491,627 to Zhang et al. These references are incorporated herein by reference as though fully set forth herein. These systems are generally referred to as Computer-Aided Diagnosis systems, Computer-Aided Detection systems, or simply, CAD systems. Such systems are believed to be particularly useful to radiologists and other medical specialists in diagnostic processes and specifically in radiologic screening procedures.
In a radiologic screening procedure, such as screening mammography, true abnormalities such as cancers are believed to occur at a typical rate of about one case per two hundred patient examinations. It is believed a CAD system, serving as an electronic reminder or second reader, can assist radiologists in obtaining higher detection rates, or higher sensitivity for abnormalities. Additionally, such CAD systems can assist radiologists in reducing the misdiagnosis rate, or lowering the false negative rate. Thus, it is believed that the use of such CAD systems will continue to increase.
Since such CAD systems typically operate on medical images in high-resolution digital format, film-based medical images ordinarily must be scanned by a high resolution scanner to convert the image data into digital form. With current CAD systems, however, we have found that systems for loading and feeding film-based medical images to the scanner are inadequate in that they tend to require too much time and effort from the user. Additionally, we have found that currently available systems do not allow the user to simply and conveniently enter case information, monitor the status of cases, and abort or adjust the processing of films being processed. For example, with currently available systems, errors in film orientation may not be detected until the radiologist views the analyzed image.
Using a light box, radiologists typically look at X-ray films such as mammograms or chest images, in a very well-defined orientation and order. For example, a mammogram typically contains four (4) films, the Cranial Caudal (“CC”) and Medio-Lateral Oblique (“MLO”) views of each of the left and right breasts. In most clinics the four films are arranged on a light box in a particular order and orientation, however in other clinics the films may be in a different order and orientation. The important point however, is that a radiologist in a given clinic is very accustomed to the same, unchanging order and orientation. When a computer is used to digitize, analyze, and/or display the images with or without some annotation, it is important that the computer display the same order and orientation of the film series that a doctor is accustomed to using to view the films.
One way of insuring correct order and orientation is to require that the images be input into the computer in a predefined order and orientation. This in fact is the present method used by the Computer Aided Detection (CAD) device ImageChecker, as described in U.S. Pat. No. 5,729,620 to Wang entitled “Computer-Aided Diagnosis System and Method,” the disclosure of which is hereby incorporated by reference in the present application. Experience has shown, however, that this requirement places some burden on the technologist operating the system, adding to the time required to do the work, and occasionally being a source of error.
For the technologist to align all films in each case in a prescribed manner would be onerous, time consuming, and prone to error. Statistically, with any order and any orientation equally likely, the probability that a random order of the four films of a standard mammogram is correct can be expressed as p=1/(84×4!)=1/(4096×24)=1/98,304=1.02×10−5 where four (4) films can be in 8 orientations and placed in four (4) different positions in an order. Thus, it would be advantageous to input a set of films in any order or orientation and have them processed and displayed in a preferred order and orientation.